Defects and prevention methods caused by springs during heat treatment such as quenching, tempering, annealing, etc.

Spring is a basic part with large quantity and wide range. It is a very important part for power machinery, instrumentation, etc. Its function is to convert mechanical function or kinetic energy into deformation energy, or to convert deformation energy into kinetic energy or mechanical work, in order to achieve the purpose of buffering and shock absorption. Since springs are widely used, this article briefly introduces some thermal coil springs and heat treatment defects and their preventive measures.

Thermal coil spring and heat treatment defects and their preventive measures

1) Hot coil spring defects and their prevention

1. The end of the support ring extends beyond the spring ring. This is related to the improper flattening and arc bending of the ends.

2. Scratches and hammer marks are related to improper operation.

3. The spring tilt is too large, which is related to factors such as improper correction, uneven spring end face, uneven heating temperature of steel materials, etc.

4. The surface of the spring is seriously oxidized and decarburized, which is related to the high furnace temperature.

5. Uneven spring pitch is related to equipment accuracy and improper pitch adjustment.

6. Overheating or overburning is related to the furnace temperature being too high.

7. Rolling cracks can only be scrapped, which is related to material defects. The inspection of raw steel should be strengthened.

8. The end of the spring is facing backward, which is related to the improper flattening shape.

9. The spring diameter is unqualified, which is related to the improper size of the mandrel.

10. Excessive bending deformation of the spring is related to uneven heating and improper spring coiling process.

2) Defects generated during the quenching and tempering process of springs. Various defects generated during the hot coil spring process can only intensify their harmfulness during quenching. Therefore, qualified hot coil springs are a prerequisite for reducing heat treatment waste. In fact, springs will produce new defects during the heat treatment process, mainly including:

1. The depth of the decarburization layer on the spring surface exceeds the standard. This is related to the fact that the temperature of the heating culvert is too high, the holding time is too long, and the protective gas heating is not used.

2. Quenching cracks, especially this defect is prone to occur during water quenching. The reasons include: internal defects in the material, excessive quenching heating temperature, improper quenching water cooling, etc.

3. Coarse grains and coarsening of the microstructure cause the spring to become brittle. The way to overcome this is to prevent the steel from overheating.

4. Uneven hardness or insufficient hardness. The main reasons are uneven heating, too low spring temperature and insufficient cooling capacity of the quenching medium.

5. Quenching deformation. Such as spring tilt, excessive bending, uneven pitch, etc., the above shortcomings can be overcome by using the quenching method of the mold pressing device.

This article briefly introduces the measures that are likely to occur in springs during hot coil springs and heat treatment, as well as some simple prevention methods. Zhengzhou Gou's is a manufacturer specializing in the manufacturing and sales of induction heating equipment such as high-frequency quenching equipment, medium-frequency induction heating equipment, ultrasonic quenching equipment, CNC quenching machine tools, etc. We have accumulated rich experience in the heat treatment of workpieces. If you have any questions about induction heating, please feel free to contact us.